BreastScreen Norway 30 years
Report
|Published
This report summarizes results from 30 years of organized mammographic screening in Norway, with a particular focus on the last five-year period, and presents perspectives on the future screening program.
Key message
BreastScreen Norway has evolved from a pilot project in 1995/96 into a nationwide screening program that has invited 1.3 million women and detected more than 31,000 ductal carcinoma in situ (DCIS) and invasive breast cancers.
The results demonstrate a mature and high-performing screening program. BreastScreen Norway continues to detect breast cancers with favorable prognostic characteristics, including a high proportion of early-stage disease. This is consistent with the program’s goal of reducing breast cancer mortality.
Attendance has increased in recent years and is now about 80%, reflecting public trust and strong engagement among women targeted by the program. Regular attendance is associated with more favorable early performance measures than irregular attendance.
A major strength of the program is its comprehensive quality assurance system, built on close collaboration with the breast centers, systematic monitoring and a unique national infrastructure for data collection, evaluation and research.
These elements have been used to generate substantial knowledge on early detection of breast cancer and mammographic screening through more than 400 publications originating from the program. This knowledge provides a strong basis for the continuous improvement of BreastScreen Norway.
Summary
BreastScreen Norway was introduced in four counties in 1995/96 and became nationwide in 2005. The program currently targets approximately 700,000 women aged 50–69, who are offered mammographic screening every two years. Since its introduction, BreastScreen Norway has sent more than 7 million invitations and performed 5.4 million screening examinations among 1.1 million women.
Overall, this report shows stable and robust results over the program’s 30-year history, which provide a solid foundation for further development, including implementation of new technologies and more personalized screening strategies.
Attendance
Among women who have received ten invitations to BreastScreen Norway, 93% have attended at least once. Annual attendance has increased from an average of 76% during the first 25 years to 78% during the period 2021–2025. In 2025, attendance reached almost 80%, the highest rate since the program became nationwide. Introduction of SMS reminders probably contributed to this increase. During 2021–2025, Fonna, Nordland, Rogaland and Sogn og Fjordane had the highest attendance rates, all exceeding 81%.
Attendance remained substantially lower among immigrant women than among non-immigrant women. During 2021–2025, 58% of immigrant women attended, compared to 81% of non-immigrants. The introduction of SMS reminders increased attendance rates in 2025 also among immigrant groups.
Recall for further assessment
The recall rate due to mammographic findings remained stable at 3–4% throughout the program’s 30-year history. During 2021–2025, the rate was 3.1%, ranging from 1.6% in Telemark to 3.9% in Oslo. For prevalently screened women, the rate was 7.0%, while it was 2.4% among subsequently screened women. For regularly screened women, the rate was 2.2% while it was 3.4% for irregularly screened.
Among women who underwent further assessment, 56% had additional imaging only, while the remaining women also underwent needle biopsy.
Breast cancer detection
More than 31,400 breast cancers were detected in BreastScreen Norway, including 5,500 (18%) ductal carcinoma in situ (DCIS).
The detection rate was at its lowest (5.3 per 1000 screening examinations) in the years after the nationwide implementation and reached 6.4 during 2021–2025. For the last 5-year period, the detection rate was 7.7 for prevalently screened and 6.1 for subsequently screened. The rate was 5.7 for women who attended regularly and 9.7 for those who attended irregularly.
Approximately 8,400 interval cancers were diagnosed, accounting for nearly one quarter of all breast cancers detected. More than 65% of the interval cancers were diagnosed in the second year of the screening interval. The interval cancer rate has remained stable since the program started at approximately 1.8 per 1,000 screened women. For women screened 2019–2023, the rate was 1.9.
Histopathologic tumor characteristics
Screen-detected cancers generally had more favorable prognostic characteristics than interval cancers. They had smaller median tumor diameter (12.7 vs. 17 mm) and were less likely to involve lymph nodes (16 vs. 25%).
These findings indicate that breast cancers detected through screening are generally identified earlier and before the disease has progressed into symptomatic cancers. This is associated with more favorable prognosis, which is confirmed by studies showing reduced breast cancer mortality among women invited and women who actually attended BreastScreen Norway.